Heteroaryl inhibitors of PAD4

A compound of formula I′:

• or a pharmaceutically acceptable salt thereof, wherein:
• Ring A is
• wherein Ring A is optionally substituted with 1-4 groups selected from fluorine, —CN, —OR, or C1-6 aliphatic optionally substituted with 1-3 fluorine atoms;
• Ring B is a 5 membered heteroaryl ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulfur;
• R1 is hydrogen, —Cy, or C1-6 aliphatic optionally substituted with —Cy and optionally further substituted with 1-4 groups selected from fluorine, —CN, or —OR;
• each —Cy is independently a 6-membered aryl ring containing 0-2 nitrogen atoms, or a 4-7 membered saturated monocyclic ring having 0-2 heteroatoms independently selected from nitrogen, oxygen, or sulphur, wherein —Cy is optionally substituted with 1-4 groups selected from fluorine, —CN, or —OR;
• R2 is hydrogen, —CN, —OR, —Cy, or C1-10 aliphatic optionally substituted with —Cy and optionally further substituted with 1-5 groups selected from fluorine, —CN, or —OR;
• or:
• two R2 groups on the same carbon are optionally taken together to form ═O;
• n is 1, 2, or 3;
• X1 is N or C(R3);
• R3 is —R, halogen, or —OR;
• each R is independently hydrogen or C1-6 aliphatic optionally substituted with 1-3 fluorine atoms;
• L is selected from a covalent bond or a C1-6 membered straight or branched, saturated or unsaturated hydrocarbon chain wherein one methylene unit of L is optionally replaced by —S(O)2— or —C(O)N(Ry)—, wherein Ry is R or —CH2phenyl;
• and
• R4 is halogen, R, phenyl, or a 5-6-membered heteroaryl ring having 1-3 heteroatoms independently selected from nitrogen, oxygen, or sulphur, wherein R4 is optionally substituted with 1-4 groups independently selected from halogen, —CN, —OR, —C(O)OH, or C1-6 aliphatic optionally substituted with 1-3 fluorine atoms;
• provided the following compounds are excluded: